Condensing type clothes dryer having a heat pump cycle and a method for controlling a condensing type clothes dryer having a heat pump cycle

ABSTRACT

A condensing type clothes dryer having a heat pump cycle and a method for controlling a condensing type clothes dryer having a heat pump cycle are provided. The condensing type clothes dryer may include a drum in which an object to be dried may be accommodated; a circulation duct that forms a circulation passage such that air may circulate via the drum; a circulation fan configured to circulate the air along the circulation duct; a heat pump cycle having an evaporator and a condenser spaced from each other in the circulation duct, and configured to absorb heat of air discharged from the drum through the evaporator and to transfer the heat to air introduced into the drum through the condenser using an operation fluid which may circulate via the evaporator and the condenser; a bypass flow path formed at the circulation duct such that a portion of air discharged from the drum may bypass the evaporator to be mixed with air having passed through the evaporator at an upstream side of the condenser; and an opening and closing device installed at the bypass flow path and configured to selectively open or close the bypass flow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of prior U.S. patentapplication Ser. No. 14/959,552 filed Dec. 4, 2015, which claimspriority under 35 U.S.C. § 119 to Korean Application No.10-2014-0175163, filed in Korea on Dec. 8, 2014, whose entiredisclosures are hereby incorporated by reference.

BACKGROUND 1. Field

A condensing type clothes dryer having a heat pump cycle, and a methodfor controlling a condensing type clothes dryer having a heat pump cycleare disclosed herein.

2. Background

Generally, a clothes dryer is an apparatus for drying laundry byevaporating moisture contained in the laundry, by blowing a hot blastgenerated by a heater into a drum. The clothes dryer may be classifiedinto an exhausting type clothes dryer and a condensing type clothesdryer according to a processing method of humid air having passedthrough a drum after drying laundry.

In the exhausting type clothes dryer, humid air having passed through adrum is exhausted outside of the clothes dryer. On the other hand, inthe condensing type clothes dryer, humid air having passed through adrum is circulated without being exhausted outside of the clothes dryer.Then, the humid air is cooled to a temperature less than a dew-pointtemperature by a condenser, so moisture included in the humid air iscondensed.

In the condensing type clothes dryer, condensate water condensed by acondenser is heated by a heater, and then heated air is introduced intoa drum. While humid air is cooled to be condensed, thermal energy of airis lost. In order to heat the air to a temperature high enough to drylaundry, an additional heater is required.

In the exhausting type clothes dryer, air of high temperature and highhumidity should be exhausted outside of the clothes dryer, and externalair of room temperature should be introduced to be heated to a requiredtemperature by a heater. As drying processes are executed, airdischarged from an outlet of the drum has low humidity. The air is notused to dry laundry, but rather, is exhausted outside of the clothesdryer. As a result, a heat quantity of the air is lost. This may degradethermal efficiency.

Recently, a clothes dryer having a heat pump cycle, capable of enhancingenergy efficiency by collecting energy discharged from a drum and byheating air introduced into the drum using the energy, has beendeveloped.

FIG. 1 is a schematic view of a related art condensing type clothesdryer having a heat pump cycle. Referring to FIG. 1, the condensing typeclothes dryer may include a drum 1 into which laundry may be introduced,a circulation duct 2 that provides a passage such that air circulatesvia the drum 1, a circulation fan 3 configured to move circulating airalong the circulation duct 2, and a heat pump cycle 4 having anevaporator 5 and a condenser 6 serially installed at or along thecirculation duct 2 such that air circulating along the circulation duct2 passes through the evaporator 5 and the condenser 6. The heat pumpcycle 4 may include a circulation pipe that may form the circulationpassage such that a refrigerant circulates via the evaporator 5 and thecondenser 6, and a compressor 7 and an expansion valve 8 installed at oralong the circulation pipe between the evaporator 5 and the condenser 6.

In the heat pump cycle 4, thermal energy of air having passed throughthe drum 1 may be transferred to a refrigerant via the evaporator 5, andthen the thermal energy of the refrigerant may be transferred to airintroduced into the drum 1 via the condenser 6. With such aconfiguration, a hot blast may be generated using thermal energydiscarded by the conventional exhausting type clothes dryer or lost inthe conventional condensing type clothes dryer.

FIG. 2 is a schematic view illustrating a flow of air passing throughthe evaporator 5 and the condenser 6, in a related art condensing typeclothes dryer to which the heat pump cycle 4 has been applied. Referringto FIG. 2, air discharged from the drum 1 may pass through theevaporator 5 and the condenser 6 sequentially, along the circulationduct 2. The circulation duct 2 and the evaporator 5 (or the condenser 6)may be formed to have no gap therebetween, such that a largest amount ofair passes through the evaporator 5 and the condenser 6. Such aconfiguration is advantageous in that a drying time and an the amount ofenergy used may be reduced, as heat exchange efficiency is enhanced as aspeed of air passing through the evaporator 5 and the condenser 6 and aheat transfer coefficient are increased.

However, such a structure where there is no gap between the circulationduct 2 and a heat exchanger (including the evaporator 5 and thecondenser 6) may have the following problems. Generally, as atemperature of the outlet of the drum 1 is increased during a dryingprocess, an evaporation pressure of a refrigerant evaporated by theevaporator 5, and a condensation pressure of a refrigerant condensed bythe condenser 6 are increased. Further, in a case in which an amount ofa drying load is large or an amount of water contained in an object tobe dried is large, a condensation pressure may be increased to a valuemore than a reliable pressure of the compressor 7 as a drying process isexecuted. As a result, a condensation temperature of the condenser 6 anda discharge temperature of the compressor 7 are increased, which maycause many problems. Accordingly, the condensation temperature of thecondenser 6 and the discharge temperature of the compressor 7 arecontrolled to be lower than a predetermined value.

More specifically, the following methods may be performed. For example,an inverter compressor may be formed to have its rpm changeable. Thus,if a condensation pressure of a condenser is increased, an rpm of theinverter compressor may be controlled to be lower than a referencecondensation pressure. However, in the inverter compressor, as a DCpower is used as a driving power source, a driver for converting an ACpower into a DC power and converting a current frequency into a requiredfrequency should be installed. This may increase fabrication costs.

FIG. 3 is a view illustrating that a secondary condenser and a coolingfan may be added to a heat pump cycle applied to a related artcondensing type clothes dryer. A secondary condenser 26 and a coolingfan 23 may be mounted adjacent to a primary condenser 16 of the heatpump cycle 4. When a temperature of the primary condenser 16 isincreased to a value greater than a predetermined temperature, thesecondary condenser 26 and the cooling fan 23 cool the primary condenser16 using air which is outside of the clothes dryer, and radiateadditional thermal energy inside of the heat pump cycle. In this case,an installation cost of the secondary condenser 26 and the cooling fan23 may increase fabrication costs.

FIG. 4 is a graph illustrating pressure-time relation when a constantspeed type compressor is turned on/off. In a related art method forcontrolling a constant speed type compressor, as shown in FIG. 4, when acondensation pressure of a condenser reaches a reference value, thecompressor may be temporarily stopped. Then, the compressor may berestarted such that the condensation pressure is maintained at a levelless than the reference value. However, as the compressor may be stoppedand restarted repeatedly, a drying time may be increased. This may causeenergy for driving the circulation fan and the drum to be wasted.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the followingdrawings in which like reference numerals refer to like elements, andwherein:

FIG. 1 is a schematic view of a related art condensing type clothesdryer to which a heat pump cycle is applied;

FIG. 2 is a schematic view illustrating a flow of air passing through anevaporator and a condenser, in a related art condensing type clothesdryer to which a heat pump cycle is applied;

FIG. 3 is a view illustrating that a secondary condenser and a coolingfan may be added to a heat pump cycle applied to a related artcondensing type clothes dryer;

FIG. 4 is a graph illustrating pressure-time relation when a constantspeed type compressor is turned on/off;

FIG. 5 is a schematic view of a condensing type clothes dryer having aheat pump cycle according to an embodiment;

FIG. 6 is a view illustrating a bypass flow path in a closed state in acirculation duct according to an embodiment;

FIG. 7 is a view illustrating the bypass flow path of FIG. 6 in an openstate;

FIG. 8 is a schematic view illustrating an opening and closing deviceconfigured to open and close the bypass flow path according to anembodiment;

FIG. 9 is a graph illustrating pressure-enthalpy (PH) relation whenthere is a bypass flow path and when there is no bypass flow path; and

FIG. 10 is a flowchart of a method for controlling a condensing typeclothes dryer having a heat pump cycle according to an embodiment.

DETAILED DESCRIPTION

Description will now be given in detail of a condensing type clothesdryer having a heat pump cycle and a method for controlling a condensingtype clothes dryer having a heat pump cycle according to embodiments,with reference to the accompanying drawings. For the sake of briefdescription with reference to the drawings, the same or like componentswill be provided with the same or like reference numbers, anddescription thereof will not be repeated. A singular expression in thespecification includes a plural meaning unless it is contextuallydefinitely represented.

Embodiments relate to a condensing type clothes dryer capable ofcontrolling an evaporation pressure and a condensation pressure whichincrease as a drying process is executed, to be less than predeterminedvalues, and a method for controlling a condensing type clothes dryerhaving a heat pump cycle.

FIG. 5 is a schematic view of a condensing type clothes dryer having aheat pump cycle according to an embodiment. The condensing type clothesdryer according to an embodiment may include a case, and a drum 110 inwhich an object to be dried may be accommodated. The case may form anouter appearance of the condensing type clothes dryer, and may beprovided with a circular opening on a front surface thereof. An objectto be dried may be introduced through the opening. A door may behinge-coupled to one side of the front surface of the case, to open andclose the opening.

The case may be provided with a control panel, which may be provided ata front upper end of the case, for facilitation of a user'smanipulation. The control panel may be provided with an input throughwhich various functions of the clothes dryer, for example, may be input,and a display that displays an operation state of the clothes dryerduring a drying function.

The drum 110 may have a cylindrical shape. The drum 110 may be rotatablyinstalled in the case, in a horizontally-laid state. The drum 110 may bedriven using a rotational force of a drive motor as a drive source. Abelt (not shown) may be wound on an outer circumferential surface of thedrum 110, and a portion of the belt may be connected to an output shaftof the drive motor. With such a configuration, once the drive motor isdriven, a drive force may be transmitted to the drum 110 through thebelt, thereby rotating the drum 110.

A plurality of lifters may be installed in the drum 110, and an objectto be dried, such as wet clothes (laundry) having been completelywashed, may be rotated by the plurality of lifters when the drum 110 isrotated. Then, the object to be dried may be dropped within the drum 110by gravity from a top of a rotation orbit trajectory (tumblingoperation). As such processes may be repeatedly performed, the object tobe dried may be dried in the drum 110. This can shorten a drying timeand enhance a drying efficiency.

The condensing type clothes dryer may be provided with the circulationduct 120 forming an air circulating passage in the case such that aircirculates via the drum 110. The circulation duct 120 may include first,second, and third ducts. The first duct may connect an outlet of acondenser 142 with a rear surface of the drum 110 (an inlet of the drum110), so air discharged from the condenser 142 may be introduced intothe drum 110. The second duct may connect an inlet of an evaporator 141with a front surface of the drum 110 (an outlet of the drum 110 based onan air flow direction), so air discharged from the drum 110 may beintroduced into the inlet of the evaporator 141. The third duct mayconnect an outlet of the evaporator 141 with an inlet of the condenser142, so air discharged from the evaporator 141 may be introduced intothe inlet of the condenser 142. Air may circulate through the condenser142, the drum 110, and the evaporator 141 through the circulation duct120, including the first to third ducts.

The condensing type clothes dryer may include a circulation fan 130configured to circulate air along the circulation duct 120. Thecirculation fan 130 may be connected to a drive motor. Morespecifically, a belt may be connected to a first side or end of anoutput shaft of the drive motor, and the circulation fan 130 may beconnected to a second side or end of the output shaft.

The condensing type clothes dryer may be provided with the heat pumpcycle 140. The heat pump cycle 140 may be configured to absorb heat froma low-temperature heat source, such as air, discharged from the outletof the drum 110, to store a high temperature-heat source in an operationfluid (a refrigerant), and to radiate heat to air introduced into theinlet of the drum 110. With such a configuration, heat discarded throughair discharged from the drum 110 may be collected, and the collectedheat may be used to heat air introduced into the drum 110.

The heat pump cycle 140 may include the evaporator 141, the condenser142, a compressor 143, and an expansion device 144. The heat pump cycle140 may be provided with a circulation pipe along which an operationfluid (a refrigerant) may circulate. The circulation pipe may beseparately formed from the circulation duct 120. A refrigerant maycirculate through the evaporator 141, the condenser 142, the compressor143, and the expansion device 144, as the evaporator 141, the condenser142, the compressor 143, and the expansion device 144 may be connectedto each other by the circulation duct 120. The circulation duct 120 andthe circulation pipe may commonly pass through the evaporator 141 andthe condenser 142. That is, air of the circulation duct 120 and arefrigerant of the circulation pipe may commonly pass through theevaporator 141. Accordingly, the air and the refrigerant may performheat exchange at the evaporator 141.

A pressure sensor 145 a may be installed in or at the evaporator 141that measures an evaporation pressure. A pressure sensor 145 b may beinstalled in or at the condenser 142 to measure a condensation pressure.

The evaporator 141 may be a fin and tube-type heat exchanger including aplurality of heat transfer plates and a plurality of heat transfer pipeshaving a refrigerant passage. The plurality of heat transfer plates maybe spaced from each other in a direction crossing an air movingdirection, and provided so as to extend perpendicular to a groundsurface. With such a configuration, air may pass through an air passageformed between the plurality of heat transfer plates when passingthrough the evaporator. The plurality of heat transfer pipes may havetherein a refrigerant passage along which a refrigerant may flow. Theplurality of heat transfer pipes may be coupled to the plurality of heattransfer plates in a penetrating manner, and the plurality of heattransfer pipes may be spaced from each other in a vertical direction.The plurality of heat transfer pipes may be connected to each other by aplurality of connection pipes bent in a semi-circular shape. As theplurality of heat transfer pipes penetrate the plurality of heattransfer plates a plurality of times, a contact area between theplurality of heat transfer plates and air may be increased. Theplurality of heat transfer plates may increase a heat transfer areabetween a refrigerant of the plurality of heat transfer pipes and air,and exchange heat transferred from the plurality of heat transfer pipeswith heat of air by contacting the plurality of heat transfer pipes.

Air may pass through the evaporator 141 as follows. Air may beintroduced into an inlet of an air passage of the evaporator 141, maymove along the air passage, and then may be discharged to an outlet ofthe air passage of the evaporator 141. A refrigerant may pass throughthe evaporator 141 as follows. A refrigerant may be introduced into aninlet of a refrigerant passage of the evaporator 141, may move along therefrigerant passage, and then may be discharged to an outlet of therefrigerant passage of the evaporator 141. As the air passage betweenthe plurality of heat transfer plates may be separated from therefrigerant passage by the heat transfer pipe, air and a refrigerant maybe heat-exchanged with each other without being mixed with each other.

The condenser 142 may have a same configuration as the evaporator 141.Even if the condenser 142 has a different operation from the evaporator141, it may also be a heat exchanger for heat exchange or heat transferbetween air and a refrigerant. The evaporator 141 or the condenser 142may be a plate-type heat exchanger in which first heat transfer plateshaving an air passage and second heat transfer plates having arefrigerant passage may be alternately laminated on each other.

In the condensing type clothes dryer, a temperature of air dischargedfrom the outlet of the drum 110 may be lower than a temperature of airintroduced into the inlet of the drum 110. However, the temperature ofthe air discharged from the outlet of the drum 110 may be sufficient forthe evaporator 141 to absorb heat of air discharged from the outlet ofthe drum 110.

The evaporator 141 may be installed in or along the circulation duct120. The evaporator 141 may be connected to the outlet of the drum 110by the circulation duct 120 (second duct), thereby absorbing heat fromair discharged from the outlet of the drum 110. That is, heat of air maybe transferred to a refrigerant at the evaporator 141. Air at the outletof the drum 110 may be cooled as its thermal energy may be lost at theevaporator 141, and then discharged from the outlet of the evaporator141. As the air discharged from the outlet of the drum 110 may be in ahumid state, the evaporator 141 may execute a dehumidifying process bycooling the air discharged from the outlet of the drum 110. On the otherhand, a refrigerant may be heated as it absorbs thermal energy at theevaporator 141, and then may be discharged from the outlet of theevaporator 141.

The condenser 142 may be installed in or along the circulation duct 120.The condenser 142 may be spaced from the evaporator 141 in thecirculation duct 120. The condenser 142 may be connected to the outletof the evaporator 141 by the circulation duct (third duct), so airdischarged from the evaporator 141 may be introduced into the inlet ofthe condenser 142. A refrigerant passing through the condenser 142 mayreceive heat from air at the outlet of the drum 110, and may transferthe heat to air at the condenser 142. The air introduced into thecondenser 142 may be heated in the condenser 142, may be discharged fromthe outlet of the condenser 142, and may be introduced into the inlet ofthe drum 110. On the other hand, a refrigerant may radiate heat in thecondenser 142, and may be condensed into a liquid state. Then, therefrigerant may be discharged from the outlet of the condenser 142. Whenthe refrigerant has a state change from a gaseous state of hightemperature and high pressure to a liquid state of high temperature andhigh pressure, condensation latent heat is generated. The generatedcondensation latent heat may be radiated to air introduced into the drum110, and the radiated heat may be used to heat air introduced into thedrum 110.

In order to transfer heat from the evaporator 141 (a low temperaturecomponent that receives heat) to the condenser 142 (a high temperaturecomponent that radiates heat), driving energy is required. In anembodiment, electric energy may be used as the driving energy. Theelectric energy may be used to drive the compressor 143 to compress anoperation fluid (a refrigerant) of the heat pump cycle 140.Alternatively, thermal energy may be used as the driving energy. Forinstance, an absorption type heat pump using vapor, high temperaturewater, or combustion gas, for example, may be used. Still alternatively,a drive force may be obtained from an engine that directly combustsfuel, and then may be used to drive the compressor 143 to compress arefrigerant. Still alternatively, a heat pump may be operated using anengine that combusts a gas. Still alternatively, a drive force may beobtained from a stirling engine driven by a heat source. The heat pumpsystem has an advantage in that a larger amount of energy than drivingenergy is supplied in the form of thermal energy. This may enhanceenergy efficiency.

The vapor compression type heat pump cycle 140, driven by electricenergy, may include of the compressor 143, the condenser 142, theexpansion device 144, and the evaporator 141. The compressor 143 may beconnected to each of the evaporator 141 and the condenser 142 by acirculation pipe. The circulation pipe may include first to fourthpipes. The first pipe may connect the evaporator 141 with the compressor143, so a gaseous refrigerant of low temperature and low pressure,evaporated from the evaporator 141, may be discharged from the outlet ofthe evaporator 141.

The compressor 143 may compress a gaseous refrigerant of low temperatureand low pressure, into a high pressure gas having a higher temperaturethan air discharged from the drum 110. The compressor 143 may radiateheat to air introduced into the drum 110 from the refrigerant of hightemperature and high pressure. Such heat radiation may be executed inthe condenser 142, and the refrigerant may be cooled to become a liquidof high pressure. If the refrigerant is depressurized by the expansiondevice 144, such as an expansion valve or a capillary tube, for example,the temperature of the refrigerant may be drastically lowered. As aresult, the refrigerant may be converted into a saturated refrigerant oflow temperature and low pressure. If the refrigerant of low temperatureabsorbs heat from air at the outlet of the drum 110, the refrigerant maybe converted into a gas of low temperature and low pressure. If the gasof low temperature and low pressure is transferred to the compressor143, the heat pump cycle 140, by which heat absorbed by the evaporator141 is radiated by the condenser 142, may be implemented.

The condensing type clothes dryer according to an embodiment may includea bypass flow path 150 configured to control an evaporation pressure anda condensation pressure to be less than predetermined values, using abasic characteristic of the heat pump cycle 140. FIG. 6 is a viewillustrating a bypass flow path in a closed state in a circulation ductaccording to an embodiment. FIG. 7 is a view illustrating the bypassflow path of FIG. 6 in an open state. FIG. 8 is a schematic viewillustrating an opening and closing device configured to open and closethe bypass flow path according to an embodiment. FIG. 9 is a graphillustrating a pressure-enthalpy (PH) relation when there is the bypassflow path and when there is no bypass flow path.

A bypass flow path 150 may be formed at or in the circulation duct 120,such that a portion of the air discharged from the drum 110 may bypassthe evaporator 141 to thus be mixed with air having passed through theevaporator 141 at an upstream side of the condenser 142. As the airdischarged from the outlet of the drum 110 may be introduced into theinlet of the drum 110 via the evaporator 141 and the condenser 142, theupstream side of the condenser 142 may refer to a space between theevaporator 141 and the condenser 142 in the circulation duct 120.

The bypass flow path 150 may be part of the circulation duct 120. Thebypass flow path 150 may be formed inside of or outside of thecirculation duct 120. The bypass flow path 150 shown in FIG. 6 may beformed in the circulation duct 120. The bypass flow path 150 may have astructure in which a sectional area of a portion of the circulation duct120 is larger than a sectional area of the evaporator 141 at a locationof the evaporator 141 and equal to a sectional area of the condenser 142adjacent an inlet of the condenser 142, based on a direction crossing anair flow direction in the circulation duct 120 at which the evaporator141 is positioned. That is, the bypass path 150 may be formed byenlarging a sectional area of a portion of the circulation duct 120larger than a sectional area of the evaporator 141 at a locationcorresponding to the evaporator 141 and then reducing the sectional areaof the circulation duct 120 until it is equal to a sectional area of thecondenser 142 adjacent an inlet of the condenser 142, with respect to adirection crossing an air flow direction in the circulation duct 120 inwhich the evaporator 141 is positioned.

That is, in order to form the bypass flow path 150 in the circulationduct 120, the sectional area of the circulation duct 120 at which theevaporator 141 is positioned may be larger than the sectional area ofthe evaporator 141, in a direction perpendicular to an air flowdirection. As a result, a gap may be generated between the circulationduct 120 and the evaporator 141. For example, a diameter of a portion ofthe circulation duct 120 at which the evaporator 141 is installed may beincreased. The term “diameter of the circulation duct 120” may mean ahorizontal length or a height of the circulation duct 120, in a case inwhich the circulation duct 120 has a quadrangular sectional surface. Inthe case in which the circulation duct 120 has a quadrangular sectionalsurface, as a height of the circulation duct 120 may be higher than aheight of the evaporator 141, the evaporator 141 may contact a bottomsurface of the circulation duct 120, and a gap may be formed above theevaporator 141. Accordingly, the bypass flow path 150 may be formedabove the evaporator 141 with respect to a gravitational direction. Ifthe bypass flow path 150 is open, a portion of the air may bypass theevaporator 141. In this case, if air discharged from the drum 110 has atemperature of about 40° C., the air may become light due to a lowdensity. The air may move upward in the circulation duct 120.Accordingly, the bypass flow path 150 may be formed above the evaporator141.

The bypass flow path 150 may have a smaller sectional area toward adownstream side of the evaporator 141. With such a configuration, airhaving bypassed the evaporator 141 may be mixed with air having passedthrough the evaporator 141.

The bypass flow path 150 of FIG. 6 may be formed above the evaporator141, but may also be formed at various positions. For example, thebypass flow path 150 may be formed below the evaporator 141, or may beformed above and below the evaporator 141. Alternatively, the bypassflow path 150 may be formed between a side surface of the evaporator 141and the circulation duct 120. Alternatively, the bypass flow path 150may be formed to pass through an inside of the evaporator 141.

The bypass flow path 150 shown in FIG. 5 may be formed to be divergedfrom the circulation duct 120, to extend to the outside of thecirculation duct 120, and to be combined with the circulation duct 120.For example, the bypass flow path 150 may be diverged from an upstreamside of the evaporator 141 of the circulation duct 120 and may becombined with a downstream side of the evaporator 141, such that air maybypass the evaporator 141 to be mixed with air at the condenser 142. Inthis case, one side of the bypass flow path 150 may communicate with theupstream side of the evaporator 141, and another side thereof maycommunicate with a space between the downstream side of the evaporator141 and the upstream side of the condenser 142. The upstream side of theevaporator 141 may be the inlet of the evaporator 141, and thedownstream side of the evaporator 141 may be the outlet of theevaporator 141.

The condensing type clothes dryer may include an opening and closingdevice configured to selectively open and close the bypass flow path150. The opening and closing device may include a damper 151 coupled tothe bypass flow path 150 by a hinge, and an actuator configured to drivethe damper 151. The damper 151 may be a plate of a predetermined size.As a first end of the damper 151 may be hinge-coupled to the bypass flowpath 150 and a second end of the damper 151 may be rotated, the bypassflow path 150 may be opened or closed. A sealing member 152 havingelasticity may be provided at the second end of the damper 151, therebypreventing air from being introduced into the bypass flow path 150.

The actuator may be a solenoid 160 or a solenoid valve. The solenoid 160may include a housing 161, a coil 162, and a plunger 163. The coil 162may be installed in the housing 161. Once power is supplied to the coil162, magnetism may be generated from a magnetic circuit which mayenclose the coil 162. A magnetic field of the magnetic circuit maygenerate a magnetic force at the plunger 163, thereby instantaneouslymoving the plunger 163.

A connection portion 151 a that connects with the solenoid 160 may beformed on a rear surface of the damper 151. As the plunger 163 of thesolenoid 160 may be hinge-coupled to the connection portion 151 a and adrive force generated from the solenoid 160 may be transferred to thedamper 151, the damper 151 may be smoothly rotated. The actuator may bea motor or a cylinder, as well as the solenoid 160. If the damper 151 isopened or closed by the motor and the cylinder, an open degree of thedamper 151 may be precisely controlled.

The damper 151 of FIG. 6 is configured to be operated by the solenoid160. In a case of closing the bypass flow path 150, the solenoid 160installed at the bypass flow path 150 may be turned on to close thebypass flow path 150, which may be provided above the evaporator 141, asshown in FIG. 6. In this case, air discharged from the drum 110 may passthrough the evaporator 141 and the condenser 142, sequentially. Anamount of the air passing through the evaporator 141 may be the same asan amount of the air passing through the condenser 142.

When opening the bypass flow path 150, the solenoid 160 installed at thebypass flow path 150 may be turned off. As a result, the damper 151 maybe moved upward in an opening direction by air flow, as shown in FIG. 7.In this case, a portion of air discharged from the drum 110 may beintroduced into the bypass flow path 150 having a small flow resistance,and the rest of the air may pass through the evaporator 141. The amountof air passing through the evaporator 141 may be smaller than the amountof air passing through the condenser 142. The reason being, as airmoving along the bypass flow path 150 may bypass the evaporator 141 tobe mixed with air at the upstream side of the condenser 142, a sum of anamount of the air flowing along the bypass flow path 150 and the amountof the air passing through the evaporator 141 may be the same as theamount of the air passing through the condenser 142.

When the damper 151 is open, a portion of wet air at the inlet of theevaporator 141 may be bypassed. This may reduce thermal energy of theevaporator 141, resulting in a lowering of an evaporation pressure.Further, as air which should pass through the evaporator 141 passesthrough the bypass flow path 150 having a relatively small flowresistance, a flow resistance of the entire air flow may be reduced.This may increase an air volume. A radiation function may be enhanced asan amount of air passing through the condenser 142 is increased. Withsuch effects, a condensation pressure may be maintained as a value lessthan a reference pressure, as shown in FIG. 9. Further, even if aconstant speed type compressor is used, the cycle may be continuouslyoperated, and a drastic decrease in dehumidifying efficiency may beprevented.

FIG. 10 is a flowchart of a method for controlling a condensing typeclothes dryer having a heat pump cycle according to an embodiment. Themethod for controlling a condensing type clothes dryer having a heatpump cycle according to an embodiment may be a method for controlling anevaporation pressure of an evaporator, such as evaporator 141 of FIG. 5,to be a value less than a predetermined pressure, by controlling an opendegree of a bypass flow path, such as bypass flow path 150 of FIG. 5.

The condensing type clothes dryer may include a circulation duct, suchas circulation duct 120 of FIG. 5, which may form a circulation passagesuch that air may circulate via a drum, such as drum 110 of FIG. 5. Thecondensing type clothes dryer may also include a heat pump cycle, suchas heat pump cycle 140 of FIG. 5 having evaporator 141 and a condenser,such as condenser 142 of FIG. 5, spaced from each other in thecirculation duct and passing air therethrough and the heat pump cycleconfigured to absorb heat of air discharged from the drum through theevaporator, and to transfer the heat to air introduced into the drumthrough the condenser using an operation fluid which circulates via theevaporator and the condenser.

The condensing type clothes dryer may include a temperature sensor and ahumidity sensor configured to sense a temperature and a humidity at theinlet and the outlet of the drum. Temperature and humidity are controlfactors required during a drying process. Further, the condensing typeclothes dryer may include a pressure sensor, such as pressure sensor 145a or 145 b of FIG. 5, configured to measure an evaporation pressure ofthe evaporator and/or a condensation pressure of the condenser. Further,the condensing type clothes dryer may include a temperature sensorconfigured to measure an outlet temperature of each of the evaporator,the condenser, and a compressor, such as compressor 143 of FIG. 5. Thepressure sensor may be installed at each of the evaporator and thecondenser, thereby sensing an evaporation pressure and a condensationpressure.

The condensing type clothes dryer according to an embodiment may includea controller, and the controller may be configured to control an opendegree of a bypass flow path by receiving a detection signal from thepressure sensor. The method for controlling the condensing type clothesdryer according to an embodiment will be explained hereinafter.

As a predetermined period of time lapses after the condensing typeclothes dryer is operated (S120), a temperature of air discharged fromthe outlet of the drum may gradually increase. This may increase anevaporation pressure of the evaporator and a condensation pressure ofthe condenser. The pressure sensor may be configured to sense at leastone of the evaporation pressure or the condensation pressure.

The controller may compare the sensed pressure with a reference pressure(S130). If the sensed pressure is equal to or smaller than the referencepressure as a result of the comparison, the controller may transmit acontrol signal (‘ON’ signal) to a solenoid, such as solenoid 160 of FIG.6, such that air discharged from the drum may be introduced into theinlet of the evaporator, thereby closing a damper, such as damper 151 ofFIG. 6 (S110).

If the damper, such as damper 151 of FIG. 6 is closed, air dischargedfrom the drum may pass through the evaporator. During this process, heatof the air introduced into an air passage of the evaporator may betransferred to a refrigerant introduced into a refrigerant passage ofthe evaporator. With such a configuration, wet air discharged from thedrum may be cooled by the evaporator to thus be dehumidified. The aircooled by the evaporator may be discharged from the air passage, therebybeing introduced into the condenser. All of the air discharged from theevaporator may be introduced into the condenser. The air introduced intoan air passage of the condenser may be heated by receiving heat from arefrigerant introduced into a refrigerant passage of the condenser, andthen may be introduced into the inlet of the drum.

In contrast, if the sensed pressure is larger than the referencepressure as a result of the comparison (S130), the bypass path may beopened (S140) and the air discharged from the drum may be distributed tothe bypass flow path and the evaporator formed at the circulation duct.With such a configuration, air introduced through the bypass flow pathmay bypass the evaporator, thereby mixing with air having passed throughthe evaporator at the upstream side of the condenser.

Embodiments disclosed herein provide a condensing type clothes dryerhaving a heat pump cycle, capable of resolving issues with conventionalstructure in which there is no gap between a circulation duct and a heatexchanger, by lowering an evaporation pressure and a condensationpressure which increase as a drying process is executed, to a value lessthan a required pressure, and a method for controlling a condensing typeclothes dryer having a heat pump cycle.

Embodiments disclosed herein provide a condensing type clothes dryerhaving a heat pump cycle that may include a drum where an object to bedried may be accommodated; a circulation duct which forms a circulationpassage such that air may circulate via the drum; a circulation fanconfigured to circulate the air along the circulation duct; a heat pumpcycle having an evaporator and a condenser spaced from each other in thecirculation duct, and configured to absorb heat of air discharged fromthe drum through the evaporator, and to transfer the heat to airintroduced into the drum through the condenser, using an operation fluidwhich may circulate via the evaporator and the condenser; a bypass flowpath formed at or in the circulation duct such that part or a portion ofthe air discharged from the drum may bypass the evaporator to be mixedwith air having passed through the evaporator at an upstream side of thecondenser, and an opening and closing device installed at the bypassflow path and configured to selectively open or close the bypass flowpath.

The bypass flow path may be formed in the circulation duct. The bypassflow path may be formed above the evaporator. The bypass flow path mayhave a structure where a sectional area of part of the circulation ductbecomes larger than that of the evaporator and then becomes small at aninlet of the condenser, based on a direction crossing an air flowdirection in the circulation duct where the evaporator is positioned.

The opening and closing device may include a damper coupled to thebypass flow path by a hinge, and configured to open and close the bypassflow path; and an actuator configured to rotatably drive the damper. Theactuator may be a solenoid. The solenoid may include a housing having acoil therein and a plunger connected to a rear surface of the damper andmoveably installed at the housing. When power to the coil is turned on,the plunger may be operated and thus a closed state of the damper may bemaintained. When power to the coil is turned off, the damper may be openby air flow. The heat pump cycle may include a circulation pipe whichforms a circulation passage such that the operation fluid may circulatevia the evaporator and the condenser; a compressor installed at thecirculation pipe and configured to compress the operation fluiddischarged from the evaporator and to transfer the operation fluid tothe condenser; and an expansion device installed at the circulation pipeand configured to reduce a pressure of the operation fluid dischargedfrom the condenser and to transfer the operation fluid to theevaporator.

Embodiments disclosed herein further provide a method for controlling acondensing type clothes dryer that may include a circulation duct whichmay form a circulation passage such that air circulates via the drum;and a heat pump cycle having an evaporator and a condenser spaced fromeach other in the circulation duct and configured to absorb heat of airdischarged from the drum through the evaporator and to transfer the heatto air introduced into the drum through the condenser by using anoperation fluid which circulates via the evaporator and the condenser.The method may include sensing at least one of an evaporation pressureof the evaporator or a condensation pressure of the condenser, comparingthe sensed pressure with a reference pressure, and either passing airdischarged from the drum through the evaporator and the condenser ordistributing air inside the circulation duct to a bypass flow path andthe evaporator such that at least part of the air discharged from thedrum bypasses the evaporator through the bypass flow path formed at thecirculation duct to thus be mixed with air having passed through theevaporator at an upstream side of the condenser.

The distributing may include controlling an open degree of the bypassflow path when the evaporation pressure and the condensation pressureare increased. The distributing may include controlling an open degreeof the bypass flow path when at least one of the evaporation pressure orthe condensation pressure is more than a reference pressure. The opendegree of the bypass flow path may be controlled by a damper rotatablyinstalled to open and close the bypass flow path, and an actuatorconfigured to drive the damper.

Embodiments disclosed herein may have at least the following advantages.First, as a portion of wet air provided at an inlet of the evaporatormay be bypassed, an evaporation pressure of the evaporator may belowered. Second, as air which should pass through the evaporator maypass through the bypass flow path having a relatively small flowresistance, a flow resistance of all of the air may be reduced. This mayincrease an air volume. Third, a radiation function may be enhanced as aflow amount of air passing through the condenser may be increased. Themethod for controlling a condensing type clothes dryer having a heatpump cycle may have at least the following advantages. First, as aportion of the wet air discharged from the drum may be introduced intothe bypass flow path at the upstream side of the evaporator to bypassthe evaporator, an evaporation pressure may be lowered to a value lessthan a predetermined pressure. Second, as the amount of air passingthrough the bypass flow path having a small flow resistance may belarger than the amount of air passing through the evaporator, a flowamount of air passing through the condenser may be increased to enhanceradiation performance. This may allow a condensation pressure to bemaintained at a level less than a reference pressure.

With such effects, a condensation pressure may be maintained as a valueless than a reference pressure. Further, as the cycle may becontinuously operated, a drying time may be shortened and energy may besaved. Furthermore, increase of an evaporation pressure and acondensation pressure may be prevented without using an invertercompressor or additionally mounting a secondary compressor, for example.This may reduce fabrication costs.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofsuch phrases in various places in the specification are not necessarilyall referring to the same embodiment. Further, when a particularfeature, structure, or characteristic is described in connection withany embodiment, it is submitted that it is within the purview of oneskilled in the art to effect such feature, structure, or characteristicin connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A condensing type clothes dryer having a heatpump cycle, comprising: a drum in which an object to be dried isaccommodated; a circulation duct that forms a circulation passage suchthat air circulates via the drum; a circulation fan configured tocirculate the air along the circulation duct; a heat pump cycle havingan evaporator and a condenser spaced from each other in the circulationduct, wherein the heat pump cycle is configured to absorb heat from theair discharged from the drum through the evaporator and to transfer theheat to air introduced into the drum through the condenser using anoperation fluid that circulates via the evaporator and the condenser; abypass flow path formed at the circulation duct such that a portion ofthe air discharged from the drum bypasses the evaporator to be mixedwith air having passed through the evaporator at an upstream side of thecondenser; a first pressure sensor installed in the evaporator thatmeasures an evaporation pressure; a second pressure sensor installed inthe condenser that measures a condensation pressure; an opening andclosing device provided at the bypass flow path and configured toselectively open or close the bypass flow path; and a controllerconfigured to control an open degree of the bypass flow path when theevaporation pressure or the condensation pressure is increased.
 2. Thecondensing type clothes dryer of claim 1, wherein the controllercontrols the open degree of the bypass flow path when at least one ofthe evaporation pressure or the condensation pressure is greater than areference pressure.
 3. The condensing type clothes dryer of claim 1,wherein the controller controls the opening closing device to close thebypass flow path when the evaporation pressure or the condensationpressure is equal to or smaller than the reference pressure.
 4. Thecondensing type clothes dryer of claim 1, wherein the bypass flow pathis formed in the circulation duct.
 5. The condensing type clothes dryerof claim 2, wherein the bypass flow path is formed by enlarging asectional area of a portion of the circulation duct larger than asectional area of the evaporator at a location corresponding to theevaporator and then reducing the sectional area of the circulation ductuntil it is equal to a sectional area of the condenser adjacent an inletof the condenser, with respect to a direction crossing an air flowdirection in the circulation duct in which the evaporator is positioned.6. The condensing type clothes dryer of claim 1, wherein the bypass flowpath is provided above the evaporator.
 7. The condensing type clothesdryer of claim 1, wherein the opening and closing device includes: adamper coupled to the bypass flow path by a hinge and configured to openand close the bypass flow path; and an actuator configured to rotatablydrive the damper.
 8. The condensing type clothes dryer of claim 5,wherein the actuator includes a solenoid and wherein the solenoidincludes: a housing having a coil therein; and a plunger connected to arear surface of the damper, and moveably provided at the housing,wherein when power to the coil is turned on, the plunger is operated andthus a closed state of the damper is maintained, and wherein when thepower to the coil is turned off, the damper is opened by air flow. 9.The condensing type clothes dryer of claim 8, wherein power to the coilis turned on when either the evaporation pressure or the condensationpressure is equal to or smaller than a reference pressure.
 10. Thecondensing type clothes dryer of claim 1, wherein the heat pump cycleincludes: a circulation pipe that forms a circulation passage such thatthe operation fluid circulates via the evaporator and the condenser; acompressor installed in the circulation pipe and configured to compressthe operation fluid discharged from the evaporator and to transfer theoperation fluid to the condenser; and an expansion device installed inthe circulation pipe and configured to lower a pressure of the operationfluid discharged from the condenser and to transfer the operation fluidto the evaporator.